New Species of Baleen Whale in the Gulf of Mexico

A recently published article in Marine Mammal Science indicates that the whale previously known as the Bryde’s (pronounced “broodus”) whale is actually a new whale species living in the Gulf of Mexico.

Lead author of the article, NOAA Fisheries scientist Dr. Patricia Rosel, provides the first morphological examination of a complete skull from these whales and identifies diagnostic characteristics that distinguish it from the other closely-related baleen whale species. Genetic data are provided as a second line of evidence supporting the uniqueness of the whales in the Gulf of Mexico. Together, the morphological and genetic data support that these whales represent a new species.

A Journey of Discovery

NOAA's Dr. Patricia Rosel examines Rice's whale type specimen at the Smithsonian’s National Museum of Natural History
NOAA’s Dr. Patricia Rosel examines Rice’s whale type specimen at the Smithsonian’s National Museum of Natural History.

Dr. Rosel started her journey with the now Rice’s whale back in 2008 when she and her colleague, NOAA Scientist Lynsey Wilcox (co-author on the paper), examined the first genetic data obtained from samples collected on NOAA Fisheries vessel surveys in the Gulf of Mexico and saw that it was quite different from other whales. However, Rosel and fellow NOAA scientist Dr. Keith Mullin (co-author on the paper) began collaborating on the new species even earlier. Mullin and his colleagues had been studying the whales at sea since the 1990s and believed they were rare and needed protection. These observations prompted NOAA scientists to collect the samples needed to study how closely related these whales were to other whales in the world’s oceans.

The process of formally describing a new species takes research, time, collaborations, and reviews by a number of scientific peers. Once a scientist is able to collect sufficient evidence to describe a new species, that species receives a Latin name and a “common name.” The Latin name for Rice’s whale is Balaenoptera ricei.

The name Rice’s whale is in honor of renowned American biologist Dale Rice who had a distinguished 60-year career in marine mammal science. He was the first researcher to recognize that Bryde’s whales (now Rice’s whales) are present in the Gulf of Mexico.

The Skull Reveals More

NOAA's Dr. Patricia Rosel photographs Rice's whale type specimen
NOAA’s Dr. Patricia Rosel photographs Rice’s whale type specimen.

The most noticeable morphological difference in the new species as compared to its closest relatives is found in the animal’s skull. Rosel was fortunate enough to be able to examine the skull of a Rice’s whale in 2020 after one stranded in Florida off Everglades National Park in January of 2019. While losses of individuals of a rare species are detrimental to their long-term sustainability, the death and the subsequent efforts by marine mammal stranding network responders to recover and investigate stranded animals provide scientists an opportunity to thoroughly study the animal from top to bottom, inside and out. The marine mammal stranding network works under the authority and oversight of NOAA Fisheries’ Marine Mammal Health and Stranding Response Program.

Following the examination and necropsy by biologists with NOAA Fisheries and members of the Southeast marine mammal stranding network, the whale remains were buried. A few months later, a team from the Smithsonian’s National Museum of Natural History unearthed the whale remains, took it for cleaning at the Bonehenge Whale Center in North Carolina and then transported the whale skeleton to their warehouse outside of Washington, D.C.

Last year Dr. Rosel and Dr. Tadasu Yamada, a scientist from the National Museum of Nature and Science in Japan and a co-author on the study, were able to take a closer look at the type specimen of the whale at the Smithsonian and identify differences that distinguish it from other whale species. The morphological differences, when combined with the genetic data Rosel and Wilcox had collected, were enough to distinguish this as a new species of baleen whale.

An Endangered Species

The new species retains its protected status under the Endangered Species Act as it was previously listed as an endangered subspecies (Gulf of Mexico Bryde’s whale). It is also protected under the Marine Mammal Protection Act. To date, there are fewer than 100 of these whales remaining, making them critically endangered. If the name Rice’s whale is formally accepted by the Society for Marine Mammalogy Committee on Taxonomy, NOAA Fisheries will go through the regulatory process to update the name used in the endangered species listing.

For NOAA scientists, this discovery is exciting and will allow them to better understand and protect this rare baleen whale.

Rice’s Whale Facts

  • Rice’s whales can weigh up to 60,000 pounds (that is 30 tons), which is  about five times as heavy as an elephant!
  • They can grow up to 42 feet.
  • Like their sister species, they have lateral three ridges on the top of their rostrum (upper jaw area).
  • Not much is known about their life expectancy, but closely related species reach sexual maturity at 9-years-old and can live about 60 years.
  • Biggest threats to the species include vessel strikes, ocean noise, energy exploration, development and production, oil spills and responses, entanglement in fishing gear, and ocean debris.
  • Found in the Gulf of Mexico in the Southeast United States.